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CBOR Object Signing and Encryption (cose) (WG)

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Charter (as of 2015-06-03):

Concise Binary Object Representation (CBOR, RFC 7049) is a concise binary format for the serialization of data structured to an extended version of the JSON data model. COSE seeks to create CBOR-based object signing and encryption formats. One motivation for COSE was to reuse functionality from the JOSE working group using the CBOR data representation as it is more amenable to constrained nodes and constrained node networks (RFC 7228).

The JOSE working group recently completed producing representations for cryptographic keys, message authentication (MACs), encryption, and digital signatures, using JSON representation.

The resulting formats will not be cryptographically convertible from or to JOSE formats. This lack of a need for bit-for-bit compatibility will enable some simplification in the adaptation process.

Criteria that should be considered in the decision making process, changing from JSON to CBOR encoding include:
o Maintain the current JOSE paradigms and formatting where feasible.
o Minimize message size, code size, and computational complexity to suit constrained environments, where this is expected to be used.
o Improve security
o Provide new functionality for additional use cases that were not required for JOSE.

Key management and binding of keys to identities are out of scope for the working group. The COSE WG will not innovate in terms of cryptography. The specification of algorithms in COSE is limited to those in RFCs or active IETF WG documents.

The working group will coordinate its progress with the ACE, DICE and CORE working groups to ensure that we are fulfilling the needs of these constituencies to the extent relevant to their work. Other groups may be added to this list as the set of use cases is expanded.

The WG will have two deliverables:

1. A standards-track specification covering the same cryptographic formats from JOSE, with optimizations for constrained device processing, expressed in CBOR;
2. Registration for algorithms (such as AES-CCM-8) that are appropriate for constrained environments.
The Working Group will use a wiki to track desired use cases for its work, but does not intend to publish this as an RFC.